Electro-mechanical device for forming a shed in a weaving machine

ABSTRACT

The heddles are displaced by means of an electro-static connection between a rotatable drum and electrically conductive cords or bands connected to the heddles and disposed about the drum. Electrical energization of the drum and selected cords causes an increase in frictional force between the drum and selected cords so as to cause movement of the cords with the drum and thus displacement of the heddles.

es tat [191 ELECTRO-MECHANICAL DEVICE FOR FORMING A SHED IN A WEAVINGMACHINE Inventor: Dietrich Wieland, Wendelstein,

Germany Assignee: Sulzer Brothers Ltd., Winterthur,

Switzerland Filed: Oct. 16, 1972 Appl. No.: 297,697

Foreign Application Priority Data Oct. 16, 1971 Germany 2151280 Nov. 13,1971 Germany..... 2156534 Nov. 13, 1971 Germany..... 2156533 1.1.5. CI139/55, 139/319 Int. Cl D03c 1.3/00, D03c 19/00 Field of Search 139/55,57, 59, 78, 79,

References Cited UNITED STATES PATENTS 12/1854 Bonelli 1159/59 2/1911Regal 139/319 Feb, 25, 1975 1,881,076 10/1932 Haebler 139/319 X2,204,891 6/1940 Hamilton 139/55 3,499,473 3/1970 Pend et a1 3,817,2926/1974 Doehler et a1. 139/55 FOREIGN PATENTS OR APPLICATIONS 523,0374/1955 Italy 139/59 901,396 1/1954 Germany 139/319 1,122,745 8/1968Great Britain 139/90 648,772 8/1928 France 139/319 364,239 5/1906 France139/78 510,882 10/1930 Germany 139/319 Primary Examiner-James Kee ChiAttorney, Agent, or FirmKenyon & Kenyon Reilly Carr & Chapin 57 iABSTRACT The heddles are displaced by means of an electrostaticconnection between a rotatable drum and electrically conductive cords orbands connected to the heddles and disposed about the drum, Electricalenergization of the drum and selected cords causes an increase infrictional force between the drum and selected cords so as to causemovement of the cords 'with the drum and thus displacement of theheddles.

7 Claims, 6 Drawing Figures 11 ELECTRU-MECHANICAL DEVICE FOR FORMING ASHED IN A WEAVING MACHINE This invention relates to anelectro-mechanical device for forming a shed in a weaving plane.

In order to form a shed in a weaving machine, it is known to make use ofwires or heddles having eyes through which warp threads are run. Byraising or low ering certain heddles, some of the warp threads areseparated from the others, so that a space is left between these twogroups of threads, i.e., the shed. In simple weaving machines, theseheddles are suspended in a certain sequence from shafts which raise orlower the corresponding warp threads, with all the heddles associatedwith one shaft raised or lowered by that shaft. In more complicatedweaving machines, with which the number of warp threads to be movedindependently of one another becomes very large, use is made of the socalled Jacquard machine. In this case, instead of using shafts, hookedrods or lifting wires are used to which the associated warp threads arefastened by means of harness. The motion of these hooked rods iseffected in accordance with whether or not they are, through theintermediary of a punched card and needle, pushed by means of amechanically moved set of knives or blades.

With all the known devices (disregarding the Jacquard machine which formechanical reasons nevertheless has a limited number of warp threadsthat can be moved independently of one another) it has been verydifficult to reach high weaving speeds. This is because the masses to bemoved at each change of shed, in acceleration or braking, are ofconsiderable magnitude.

Accordingly, it is an object of the invention to reduce to a minimum themasses to be moved mechanically in a shed forming mechanism of a weavingmachine.

It is another object of the invention to increase the number of warpthreads to be moved independently of each other up to the total numberof warp threads present.

Briefly, the invention provides an electro-mechanical device whichconnects to a plurality of heddles in a weaving machine so as todisplace the heddles into predetermined positions for a shed. The deviceincludes at least one rotatable drum, a plurality of electricallyconductive harness cords which are disposed over the drum with each cordbeing connected to at least one heddle, and means for creating anelectrically attractive force between selective cords and the drum formovement of the selected cords with the drum to displace the heddlesconnected thereto into the shed. In addition, each heddle is connectedto a counteracting spring at an opposite end from a harness cord. Thespring serves to maintain the heddle in a rest position and to returnthe heddle to this rest position after dis placement. Each heddle isalso connected to a prestressing spring at the harness cord end. Theprestressing spring serves to initially balance the heddle in the restposition by cooperating with the counteracting spring while also servingto reverse functions with the counteracting spring when the direction ofdrum rotation is reversed.

In operation, each heddle is fastened to a harness cord that is run,independently of all the others, over the rotating drum while thedirection in which the drum rotates is preferably such that the heddlebecomes lifted when there is sufficient friction between the drum andcord. The arrangement is such that the normal frictional force at thedrum is unable to overcome the force of the counteracting spring at theother side of the heddle. When the heddle is to be lifted, thefrictional force is increased by means of electro-static attractingforces, for example by means of the known Johnsen-Rahbek effect. Thebasis of this effect is that the friction between a bad conductor and aconductive element sliding thereon increases greatly as a result ofelectrostatic attraction, when an electric voltage is applied betweenthe bad conductor and the conductive element. When an electric voltageis applied between the drum and the part of the: harness cord lyingthereon, and made conductive, the friction between the drum and cordincreases. This effects a lifting of the heddle against the force of thecounteracting spring. When the electric voltage is switched off, theforce of the counteracting spring again dominates, so that the heddlefalls back to the rest or bottom position. With the direction ofrotation reversed, a suitable alteration of the forces of thecounteracting spring and the prestressing spring is made.

Of course, thearrangement may be suchthat the harness cords do not allrun over the same drum, but are distributed among a number of similardrums. These drums advantageously have machined grooves to guide theharness cords.

The control of the individual harness cords is advantageously carriedout by means of a suitable electronic device, which, depending on thedegree of complexity of the fabric weave to be produced, has a pluralityof outputs, whose number can be increased up to the number of warpthreads present, e.g., as described in German patent application No. IP21 52 434.5, filed Oct. 2, 1971.

It is also possible to control the individual'harness cords inchronological sequence, so that a so-called undulated shed is produced.

For simple weaves, it is indeed sufficient to work with relativelysimple electric or electronic switches, whereby the harness cords areconnected in parallel in suitable groups. For example, for theproduction of linen weave a simple switch, or an astable multivibrator,which switches over at each change of shed is sufficient. When only asimple weave is to be produced, it is also possible to groupthe harnesscords of all heddles having the same lift together and to have the drumlift them in common. Instead of cords, it may also be advantageous touse bands which slide over the drum.

The drum can naturally be disposed above and/or below the weavingmachine, whereby it is possible to arrange for high shed, low shed andupright shed.

In order to obtain sufficient attractive forces with relatively lowvoltages, use can also be made of electromagnetic attractive forces. Tothis end, the drum, for example, consists of ferromagnetic material, andthe bands or harness cords are made of a flexible ferromagneticmaterial, for example of rubber filled with weak ly-magnetic ferrite, orof a similarly filled synthetic substance, and provided with a suitablydisposed winding to produce the magnetic field.

A suitable means for retaining the displaced heddles in position in theshed can also be incorporated in the device so as to allow theelectrostatic force creating means to be deactivated. For example, oncedisplaced, each heddle can be retained by an electromagnet. Thiselectromagnet would, in turn, be actuated in synchronism with theelectrostatic force generating means and weaving machine so as torelease the heddles when the shed is no longer required, e.g., uponcompletion of a weft insertion operation.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. ll schematically illustrates a device according to the invention;

FIG. 2 illustrates a device according to the invention with a number arollers;

FIG. 3 illustrates a partial view of a drum having grooves according tothe invention;

FIG. 4 illustrates a cross-sectional view through a band for lifting theheddles according to the invention;

FIG. 5 illustrates a plan view of the band of FIG. 4; and

FIG. 6 illustrates a modified construction according to the invention.

Referring to FIG. 1, the heddles l are suspended via insulators 2 at oneend on conductive harness cords 3, and on the other end, oncounteracting springs 4. The harness cords 3 run over a drum 5, made ofa bad (i.e. poor) conductor type material, or coated with such a badconductor type material, and are at their other ends, again through theintermediary of insulators 2, fastened to prestressing springs 6. Anelectric connection is made through a slide-contact 7 on the drum 5 andthrough connection wires 8 for the individual harness cords 3 in asuitable manner.

Referring to FIG. 2, instead of using a single drum, a plurality ofdrums 5 can be used with separate groups of harness cords 3 distributedamong the drums 5.

Further, referring to FIG. 3, each drum 5 can be provided with annulargrooves 9 each of which serves to guide a harness cord (not shown).

Referring to FIGS. 4 and 5, each harness cord 3 is made as a band ofrectangular cross-section and of weakly magnetic rubber. The cord 3 isprovided with a groove on one side together with an upraised portion soas to form pole surfaces 12 while allowing a winding I3 to be woundabout the upraised portion within the groove. The winding 13 has asuitable current lead-in I4 and lead-out 14 at one end of the band 3 forconnection to a suitable power source for generating a magnetic fieldvia the winding 13.

Referring to FIG. 1, in operation, while the drum 5 is rotating, currentis supplied to the drum 5 via the contact 7 while selected cords 3 areswitched-in via the wires 8 to complete corresponding selected circuits.The selection of the wires 8 to be switched-in can be accomplished via asuitable electronic control such as that mentioned above. Thereafter,because of the creation of an electrostatic force between the selectedcords 3 and the drum 5, these cords 3 are carried by the drum 5 in thedirection of drum rotation against the force of the springs 4 untilreaching a position, e.g., where the springs 4 balance the frictionforces on the cords 3. The heddles I on these selected cords 3 are thusraised to the required points in the shed.

Upon switching-out of the wires 8 from the electrical circuit, asdetermined by the electronic control, the springs 4 bias the displacedcords 3 and heddles 1 back to the initial rest position as shown in FIG.II.

In order to form a low shed, the drum 5 is rotated in the oppositedirection so as to carry the selected cords 3 and heddles I downwardly.The springs 4, 6 in this case reverse their respective functions.

Referring to FIG. 6, instead of maintaining the electrical connectionsthrough the shedding cycle of a weaving machine, a suitable restrainingmeans can be used to hold the displaced heddles in place while electrical contact is released. To this end, each band or harness cord 3 isrun over a drum 5, rotating in the direction of the arrow, and isfastened at one side through the intermediary of an insulator 2 to aheddle l and at the other side to a counteracting spring or springelement 25. This spring 25 also serves to supply current from aconnecting wire 26. The counteracting spring 25 is made as leaf-springor wire-spring, and consists of ferromagnetic material, e.g., steel. Thecounteracting spring 25 is mounted so that during a heddle-liftingoperation the spring 25 moves against an electromagnet 27 common to anumber, or many, counteracting springs 25. This position is shown by thedotted line. The counteracting spring 25 of the raised heddles 1 remains against the electromagnet 27 for as long as the electromagnet 27is excited; while the counteracting springs 25 of the not-raised heddlesdo not become influenced by the electromagnet 27.

With electrostatic excitation(for example, as described above withrespect to FIGS. 1 to 3), during a connection of the electromagnet 27with the potential (i.e. pole) of the drum 5, vanishing(i.e. shortcircuiting) of the electrostatic attraction force, between the drum 5and a cord 3 can be insured at the instant of application of thecounteracting springs 25 against the electromagnet 27.

What is claimed is:

1. In combination with a plurality of heddles for forming a shed in aweaving machine; at least one rotatable drum, a plurality ofelectrically conductive harness cords disposed over said drum, eachrespective cord being connected to at least one respective heddle, [and]means for creating an electrically attractive force between selectedcords of said harness cords and said drum for movement of said selectedcords with said drum to displace said heddles connected thereto into apredetermined position, and means for retaining the displaced heddles insaid predetermined position during deactivation of said means forcreating an electrically attractive force.

2. The combination as set forth in claim I wherein each drum includes aplurality of annular grooves for guiding said respective harness cordstherein.

3. The combination as set forth in claim 1 wherein at least some of saidcords are in the form of bands and are connected to a plurality ofheddles.

4. The combination as set forth in claim I wherein at least one cord isconstructed of a weakly magnetic material having a winding therein forproducing an electro-magnetic field.

5. The combination as set forth in claim 1, wherein said means forretaining the displaced heddles includes at least one electromagnet.

6. The combination of claim 1, wherein said means for retaining thedisplaced heddles includes a counteracting spring secured to arespective cord at one end and electrically connected at an opposite endto said means for creating an electrically attractive force to move intoa preset position upon activation of said latter means; and anelectromagnet electrically connected to said drum for retaining saidspring in said preset position after deactivation of said latter means.

6 7. In combination with a plurality of heddles for drum for movement ofsaid selected cords with said forming a shed in a weaving machine; drumduring rotation of said drum to displace said at least one rotatabledrum connected to one pole of heddles and Spring elements connectedthereto a voltage source;

a plurality of electrically conductive harness cords 5 disposed oversaid drum, each respective cord being connected to at least onerespective heddle;

a plurality of spring elements, each respective spring intopredetermined positions; and

means for retaining the displaced heddles and spring elements in saidrespective positions, said means including an electrical connection withsaid one element being Connected to a respective one of pole for shortcircuiting the electro-static attracsaid cords to move therewith and toa second pole 10 force between 531d m Selected (ford of the voltageSource; upon movement ofa respective sprmg element into means forcreating an electrically attractive force bethe respectivepredeterminedl position.

tween selected cords of said harness cords and said

1. In combination with a plurality of heddles for forming a shed in aweaving machine; at least one rotatable drum, a plurality ofelectrically conductive harness cords disposed over said drum, eachrespective cord being connected to at least one respective heddle, (and)means for creating an electrically attractive force between selectedcords of said harness cords and said drum for movement of said selectedcords with said drum to displace said heddles connected thereto into apredetermined position, and means for retaining the displaced heddles insaid predetermined position during deactivation of said means forcreating an electrically attractive force.
 2. The combination as setforth in claim 1 wherein each drum includes a plurality of annulargrooves for guiding said respective harness cords therein.
 3. Thecombination as set forth in claim 1 wherein at least some of said cordsare in the form of bands and are connected to a plurality of heddles. 4.The combination as set forth in claim 1 wherein at least one cord isconstructed of a weakly magnetic material having a winding therein forproducing an electro-magnetic field.
 5. The combination as set forth inclaim 1, wherein said means for retaining the displaced heddles includesat least one electromagnet.
 6. The combination of claim 1, wherein saidmeans for retaining the displaced heddles includes a counteractingspring secured to a respective cord at one end and electricallyconnected at an opposite end to said means for creating an electricallyattractive force to move into a preset position upon activation of saidlatter means; and an electromagnet electrically connected to said drumfor retaining said spring in said preset position after deactivation ofsaid latter means.
 7. In combination with a plurality of heddles forforming a shed in a weaving machine; at least one rotatable drumconnected to one pole of a voltage source; a plurality of electricallyconductive harness cords disposed over said drum, each respective cordbeing connected to at least one respective heddle; a plurality of springelements, each respective spring element being connected to a respectiveone of said cords to move therewith and to a second pole of the voltagesource; means for creating an electrically attractive force betweenselected cords of said harness cords and said drum for movement of saidselected cords with said drum during rotation of said drum to displacesaid heddles and spring elements connected thereto into predeterminedpositions; and means for retaining the displaced heddles and springelements in said respective positions, said means including anelectrical connection with said one pole for short circuiting theelectro-static attraction force between said drum and a selected cordupon movement of a respective spring element into the rEspectivepredetermined position.